JPH0259455B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a transparent type electrostatic recording paper, and particularly to a transparent paper-based electrostatic recording paper with excellent recording properties for use in facsimiles and high-speed printer plotters. Recently, with the development of high-speed electrostatic facsimile machines and high-speed electrostatic printer plotters, documents and drawings have come to be automatically created. However, if the output document or drawing is an original drawing for diazo copying, Alternatively, in the case of design drawings or program lists whose contents need to be checked, the electrostatic recording paper used for output needs to be as transparent as possible. Various types of transparent substrates have been tried in the past, including plastic films such as cellulose acetate and polyethylene terephthalate, tracing paper, paper mixed with synthetic pulp, and transparent paper impregnated with oils, plasticizers, etc. However, they all have the following drawbacks. That is, film-based materials have excellent transparency, dimensional stability, and mechanical strength, but lack electrostatic recording properties and have drawbacks such as foldability and cost. Tracing paper has poor dimensional stability, tear strength, water resistance, etc., and is extremely unsuitable for processing as electrostatic recording paper, such as coating and impregnation. Synthetic pulp mixed paper generally has large irregularities in texture and transparency due to the poor affinity between wood pulp and synthetic pulp, and its transparency itself is low. It has the same flaws as film. In addition, paper impregnated with oils, plasticizers, etc. as a clarifying agent,
During long-term storage or due to heat in an electrostatic recording device, the transparentizing agent migrates to other parts, causing blocking on winding, blurring of images, and poor mechanical strength. Generally, to make paper transparent, it is sufficient to fill the voids in the paper layer with a substance that has a refractive index similar to that of cellulose fibers. However, if a liquid or low-melting solid substance is used as the substance, migration of the transparentizing agent will occur, causing blocking of the winding, blurring of the image, and poor writability. On the other hand, when a high-melting point polymer substance is used as a transparentizing agent, the transparentizing agent does not penetrate into the inside of the paper layer sufficiently, making it impossible to achieve uniform transparency. Therefore, for transparency, it is best to use a transparentizing agent, i.e., a reactive resin, which is a relatively low-molecular liquid substance that can be cured by catalysts, heating, or other means after sufficiently permeating into the paper layer. This seems to be the strategy. Based on this viewpoint, Japanese Patent Publication No. 43-25927 claims the use of an alkanol-modified amino resin and a non-oil-modified or non-drying oil-fatty acid-modified short-oil alkyd resin that is compatible with the alkanol-modified amino resin. In addition, in Japanese Patent Publication No. 51-36367, diisocyanate or polyisocyanate is used as the first component, and a saturated fatty acid modified type or a non-drying oil fatty acid modified type that is compatible with diisocyanate or polyisocyanate and has 8 to 18 carbon atoms is used. 30 to 70, a molecular weight of 1000 or less, and an OH value of 10 or more, as a second component. These known resin compositions are extremely excellent as paper clarifying agents, and do not cause troubles such as blocking during winding due to migration as described above, so they are considered to be extremely promising as base materials for electrostatic recording paper. Conceivable. From this point of view, the present inventors have made various attempts to lower the volume resistivity by applying a conductive treatment agent to paper impregnated with the above-mentioned reactive resin as a base material. If the transparent paper is simply coated as a conductive layer on the front and back sides, the volume resistivity of the transparent paper base is as high as 10 ¹² Ω-cm or more, and good image recording cannot be obtained on the dielectric layer. Significant deterioration in image quality occurred in low temperature and humidity environments below 30% RH. In addition, an attempt was made to perform conductive treatment and transparent treatment in one step using the same liquid, but the compatibility between the conductive treatment agent and the transparent treatment agent was poor, and the conductive treatment agent and the reactive resin tended to react, resulting in insufficient conductivity. It was difficult to obtain good effects and sufficient transparency. As a result of intensive research to solve these problems, the present inventors impregnated paper with such reactive resins and formed a chain or network structure within the paper layer by curing. By using transparent paper as a base and re-impregnating it with a conductive treatment agent, we were able to complete an electrostatic recording paper with good transparency that does not cause deterioration in image quality not only in high humidity but also in low humidity environments. Ivy. Therefore, in order to achieve the purpose of the present invention, it is necessary to make the paper after transparentization suitable for re-impregnation with a conductive treatment agent, and the present invention uses transparent paper impregnated with a reactive resin as an electrostatic recording paper. This makes it possible to use it as a base material. A more detailed explanation will be added regarding this point. To perform conductive treatment to obtain the desired low resistance value by coating resin-impregnated transparent paper with a conductive treatment agent,
Since a large amount of coating must be applied, it is uneconomical and impractical, and it also tends to curl and has an increased tactile feel. In the normal coating amount range, fogging due to background smearing of the developing toner is likely to occur in electrostatic recording apparatuses using either single-sided control or double-sided control. On the other hand, if the re-impregnation method is used, the volume resistivity value can be easily lowered by using a small amount of conductive treatment agent. The required volume resistivity is 10 ¹¹ Ω−
cm or less, and for this purpose, it is necessary to make it easy for the conductive treatment agent to penetrate uniformly into the paper. According to research by the present inventors, the permeability of the conductive treatment agent is closely related to the air permeability of the transparent paper, and if the air permeability of the transparent paper is controlled within a certain range, the volume after re-impregnation will be We discovered that the resistance can be easily reduced to 10 ¹¹ Ω-cm or less. The drawing shows the relationship between the air permeability of transparent paper and the volume resistivity of electrically conductive treated paper. As is clear from this drawing, in order to reduce the volume resistivity to 10 ¹¹ Ω-cm or less, the air permeability of the transparent paper must be 10,000 sec or less. Note that when the air permeability of the transparent paper decreases to less than 400 seconds, the transparency becomes less than 50%, and the paper lacks practicality as a transparent type electrostatic recording paper of the present invention. Insufficient transparency makes it unsuitable for use as electrostatic recording paper, and if transparent paper with low air permeability is used, the amount of expensive conductive agent deposited exceeds 10 g/m ² due to re-impregnation. Economically unfavorable. On the other hand, air permeability 10000sec
When using the above paper, even if conductive treatment is performed by re-impregnation with a conductive agent, the amount of conductive agent deposited is as low as 1 g/m ² or less, and the volume resistivity of the treated paper exceeds 10 ¹¹ Ω-cm, making it impossible for electrostatic recording. Characteristics deteriorate. The reactive resin as a clarifying agent in the present invention is an alkanol-modified amino resin known from Japanese Patent Publication No. 43-25927 and Japanese Patent Publication No. 51-36367, and a non-oil modified or non-drying oil compatible therewith. A combination of fatty acid modified short oil type alkyd resins, or a saturated fatty acid modified type or non-drying oil fatty acid which is compatible with diisocyanate or polyisocyanate and has 8 to 18 carbon atoms. It is preferable to use a combination of modified polyester polyol resins having an oil length of 30 to 70, a molecular weight of 1000 or less, and an OH value of 10 or more as the second component. Polyamines, epoxy resins, UV curable or electron beam curable resins can also be used. A high-quality base paper for impregnation or high-quality paper having a basis weight of 20 to 100 g/m ² is impregnated with a reactive resin such as the above. The adhesion rate of the reactive resin to the substrate is preferably 10 to 60%. After transparency, paper must have a transparency of 50% or more and an air permeability of 400 to 10,000 seconds. The thus obtained resin-impregnated transparent paper is re-impregnated with a conductive treatment agent to perform conductive treatment to reduce resistance. As the conductive treatment agent, known polymer cation salts having a quaternary ammonium group such as polyvinylbenzyltrimethylammonium chloride, polydimethylarylammonium chloride, and polyN-methylvinylpyridinium chloride are particularly desirable, but other tertiary It is also possible to use an ionically conductive conductive agent having a class amino group, a sulfonium group, or a phosphonium group. Further, it is also possible to use a polymeric anion salt having a carboxyl group, sulfone group, sulfate group, phosphate group, etc. in the molecule, although the effect of imparting conductivity is somewhat inferior. It is also possible to mix or use a binder and other subcomponents with the conductive treatment agent. The conductive treatment agent is dissolved in water or a solvent such as ketone, alcohol, or ester, alone or in a mixture, and re-impregnated as a solution. Solution concentration is 10-50%
A range of is suitable. In the present invention, since the transparent paper impregnated with the reactive resin is re-impregnated with the conductive treatment agent, the effect of imparting conductivity can be obtained with a small amount of impregnation. According to experiments, the amount of impregnation is 1 to 10 as solid content.
g/m ² was sufficient. Needless to say, if a coating layer of a conductive treatment agent is further provided on the front surface, the back surface, or both the front and back surfaces after re-impregnating with the conductive treatment agent, the electrostatic recording characteristics will be further improved. The relationship between the air permeability of the transparent paper impregnated with the reactive resin and the volume resistivity of the conductive treated paper re-impregnated with the conductive agent is as shown in the drawing. After conductive treatment using a conductive treatment agent, a dielectric layer is applied. The dielectric layer is composed of one or more dielectric materials such as vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, acrylic resin, butyral resin, styrene resin, silicone resin, epoxy resin, and various copolymer resins such as the following. It uses a known resin or the like as a binder, and contains an inorganic pigment or an organic pigment in an amount equal to or less than the same weight part. Kaolin is an inorganic pigment,
Extender pigments such as calcium carbonate, barium sulfate, and amorphous silicic acid, and organic pigments include synthetic resin powders such as polyethylene powder and polystyrene powder, starch powder, and cellulose powder, and pigments such as these may be mixed. It can provide writing properties and the feel of plain paper. The coating amount of the dielectric layer is 3 to 10
g/m ² is preferred. Hereinafter, the present invention will be specifically explained with reference to Examples. Tests and evaluations of the paper in Examples were carried out using the following methods. (1) Transparency: Measured using a transparency measuring device manufactured by Toyo Seiki Seisakusho. (2) Air permeability: Conducted according to the air permeability test method of JIS P 8117. (3) Volume resistivity: Measured using Kawaguchi Electric Seisakusho VE-30 after 24 hours of humidity control at 20°C and 65% RH. (4) Image density: Record a solid black image on a 10cm x 10cm area and measure it as a reflection density using a Macbeth densitometer (RD541). If the reflection density is less than 0.5, mark it as "×". (5) Clarity: When recording size 5 type as an image, all the type can be clearly legible as 〇, all the type can be legible but there are some unclear parts as △, even a little bit is legible. Items with typefaces that cannot be written are marked as ×. (6) Fog: When solid black images are recorded at 10 cm intervals of 10 cm x 10 cm, and the margins are measured as reflection density with a Macbeth densitometer (RD541), those with a reflection density of less than 0.15 are marked with ○, and those with a reflection density of 0.15
If the reflection density is less than 0.25, it is marked △, and if the reflection density is 0.25 or more, it is marked ×. Example 1 A high-quality base paper for impregnation with a weight of 50 g/m ² was impregnated with a reactive resin having the following composition, and after removing the excess liquid with a pressurized nip roll, curing was performed at 150° C. for 3 minutes. 100 parts (all parts by weight) of a 70% xylene solution of a polyester polyol with a reaction molar ratio of 5 parts of coconut oil fatty acid, 6 parts of phthalic anhydride, and 7 parts of glycerin.A reaction molar ratio of 3 parts tolylene diisocyanate and 1 part of trimethylolpropane. 60% ethyl acetate solution of triisocyanate consisting of 47 parts ethyl acetate appropriate amount toluene appropriate amount reactive resin solid content 20; 40; 61; 65; 67; 68;
The reactive resin adhesion rate (to base paper) when 69; 70% is 6; 12; 28; 48; 56; 59; 61; 65%, and the transparency of the obtained transparent paper is 41.5; 55.0. ;
71.5; 73.5; 75.0; 75.8; 76.2; 77.0%; air permeability is 350; 400; 1000; 2100; 5000; 9200; 10300;
It was 30000sec. Using transparent paper such as this, re-impregnate with a 15% solution of polyvinylbenzyltrimethylammonium chloride (ECR77 manufactured by Dow Chemical Company), remove excess liquid with a pressure nip roll, and incubate at 100℃ for 3 minutes.
was dried. The amount of cationic polymer deposited in this case is 10.1; 8.4; 5.2; 3.4; 2.6;
1.8; 0.5; 0.3 g/m ² , and the volume resistivity of the conductive treated paper is 9.0×10 ⁷ ; 2.4×10 ⁸ ; 3.2×10 ⁹ ; 9.5×
10 ⁹ ; 5.3×10 ¹⁰ ; 9.0×10 ¹⁰ ; 1.7×10 ¹¹ ; 4.6×10 ¹¹
It was Ω-cm. Next, a dielectric layer composition consisting of 20 parts of a copolymer resin mainly composed of methyl methacrylate, 10 parts of calcium carbonate powder, and 70 parts of ethyl acetate was applied using a roll coater and dried to a dry weight of 5.3 g/m ² Forms a dielectric layer with transparency of 48.4; 58.1; 73.2;
Transparent type electrostatic recording paper (Samples No. 1 to No. 8) with a ratio of 74.7; 75.4; 75.8; 76.0; 76.5% was obtained. The electrostatic recording paper obtained in this way was transferred to a double-sided control type electrostatic recording high-speed printer plotter (manufactured by Versatech, model 1200A) and a single-sided control type electrostatic recording high-speed printer plotter (manufactured by Calcomp Corporation, model 1200A).
EPP11 inch model) at 20℃, 65%RH and 5
Images were recorded in an atmosphere of ℃ and 25% RH, and the obtained image density was measured as a reflection density using a Macbeth densitometer (RD541), and the sharpness, background smearing and fog caused by the developing toner were judged. Got the results. As is clear from Table 1, the air permeability of the transparent paper obtained by impregnating the reactive resin is about 350 seconds (sample
No. 1) has a low volume resistivity in the conductive treatment stage and has extremely good electrostatic recording properties, but because the amount of reactive resin attached is small and transparency is insufficient, the electrostatic recording paper Transparency is below 50%,
This is insufficient for use as transparent electrostatic recording paper. In addition, when transparent paper with low air permeability is used, the amount of expensive conductive agent deposited is 10g/10g after re-impregnation.
m ² and is economically undesirable. On the other hand, sample No. 7 and No. 7 have transparent paper whose air permeability is 10,000 seconds or more.
8, even if conductive treatment was performed by re-impregnating the conductive agent, the amount of the conductive agent deposited was 0.5 or 0.3 g/m2 and 1 g/ ^m2 .
m ² or less, and therefore the volume resistivity of the conductive treated paper exceeds 10 ¹¹ Ω-cm. Therefore, the electrostatic recording properties are poor, which is a practical problem, especially in a low humidity atmosphere of 5° C. and 25% RH. On the other hand, the transparent papers with air permeability in the range of 400 to 10,000 sec (Samples No. 2 to No. 6) exhibited extremely good properties in terms of transparency and electrostatic recording properties. ing.

[Table] Example 2 A conductive agent was applied to the transparent paper of Example 1 with a polyvinylbenzyltrimethylammonium chloride solution with a transparency of 71.5% and an air permeability of 1000 sec with a transparency agent adhesion rate of 28% (to base paper) and a conductive agent as in Example 1. Treatment is carried out at a concentration of cationic polymer of 5; 10; 15;
It was changed to 20; 25%. The amount of re-impregnation of the conductive agent is
0.8; 2.4; 5.2; 8.1; 10.3 g/m ² , and the volume resistivity of the treated paper is 1.2×10 ¹¹ ; 5.8×10 ¹⁰ ; 3.2×10 ⁹ ;
It was 3.4×10 ⁸ ; 1.1×10 ⁸ Ω-cm. A dielectric layer was provided on the conductive treated paper by the same method as in Example 1, and the transparency was 70.1; 71.7; 71.5;
71.3; 71.5% electrostatic recording paper (sample No. 9, 10, 3,
11, 12). The electrostatic recording paper thus obtained was heated to 65% at 20°C using the double-sided control method and the single-sided control method in the same manner as in Example 1.
Tests were conducted by recording images in an atmosphere of RH, 5°C, and 25% RH. The results obtained are shown in Table 2. As shown in Table 2, the amount of conductive agent impregnated in re-impregnation is
At 0.8 g/m ² (Sample No. 9), the volume resistivity of the electrostatic recording paper becomes slightly high, and the electrostatic recording properties are particularly poor at 5°C and low humidity of 25% for both double-sided and single-sided control systems. Regression in density, sharpness and fog is seen. Except for this, good results were obtained in all cases by re-impregnation.

[Table] Example 3 A high-quality paper weighing 50 g/m ² was impregnated with a reactive resin having the following composition, and after removing the excess liquid with a pressurized nip roll, curing was performed at 150° C. for 5 minutes. The reaction molar ratio is melamine 1, formaldehyde 4.5,
60% xylene-isobutanol equivalent solution of butoxymethylolmelamine resin consisting of 6 butanol 40 parts 60% xylene solution of coconut oil-modified alkyd resin consisting of 4 parts phthalic anhydride, 3 parts trimethylolpropane, and 1 part propylene glycol in a reaction molar ratio 60 parts xylene 20 parts This treatment results in reactive resin adhesion rate (on base paper) of 32
%, transparency of 66%, and air permeability of 2500 sec. Next, polyvinylbenzyltrimethylammonium chloride (ECR-77 manufactured by Dow Chemical Company) was
Re-impregnate with 15% solution, remove excess liquid with pressurized nip roll, dry at 100℃ for 3 minutes, impregnated amount 4.0 g/m ² , volume resistivity 6.0 × 10 ⁸ Ω-cm, transparency 66.7 % conductive treated paper was obtained. Furthermore, polyvinylbenzyltrimethylammonium chloride (ECR-77 manufactured by Dow Chemical Company) was applied to the back, front and both sides of this conductive treated paper.
Dry coating amount of 25% solution with air knife coater: 3
g/m ² (3 g/m ² for each side in the case of both sides). A dielectric layer according to Example 1 was formed on the surface of the conductive treated papers such as these, and each of the obtained electrostatic recording papers (Samples No.
The electrostatic recording characteristics of No. 16) are shown in Table 3. Comparative Example A dielectric layer according to Example 1 was formed on the surface of the transparent paper according to Example 3, and polyvinylbenzyltrimethylammonium chloride (ECR- manufactured by Dow Chemical Company) was applied to the back, front, and both front and back surfaces of the transparent paper, respectively. 77) was applied as a 15% solution using an air knife coater, with a dry coating amount of 3 g/m ²
Conductive treatment (3 g/m ² each for both sides)
Samples having a dielectric layer according to Example 1 formed on their surfaces were prepared (Samples No. 17 to No. 20), and their electrostatic recording properties were similarly investigated and compared using double-sided and single-sided control methods.
The results are also listed in Table 3.

[Table] As is clear from Table 3, all electrostatic recording papers obtained from transparent paper impregnated with a reactive resin exhibit good transparency. However, the volume resistivity was clearly lowered by re-impregnation with the conductive agent, demonstrating that the re-impregnation of the present invention is an effective means. The electrostatic recording properties are also controlled on both sides. With the electrostatic printer plotter, the image density is lower when re-impregnated at both 20℃ and 65%RH and 5℃ and 25%RH.
It is 1.1 or higher, and both clarity and fog are good, but
All samples that were not re-impregnated were defective. Also, in the single-sided control electrostatic printer plotter, the re-impregnated one of the present invention performs well, but in the comparative example without re-impregnated sample No. 2 at 20°C and 65% RH.
All except No. 19 and No. 20 were found to be defective, and it was confirmed that they were of no practical use.

[Brief explanation of the drawing]

The drawing shows the relationship between the air permeability of transparent paper impregnated with a reactive resin and the volume resistivity of conductive treated paper re-impregnated with a conductive agent.

Claims (1)

[Claims] 1 Impregnated with reactive resin and has an air permeability of 400~
Transparent type electrostatic recording paper with a transparency of 50% or more, characterized in that a dielectric layer is provided on conductive treated paper, which is 10000 sec transparent paper re-impregnated with a conductive agent.